/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.monitor;

import java.io.IOException;
import java.util.Map;
import java.util.Objects;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Query;

/** A query match containing the score explanation of the match */
public class ExplainingMatch extends QueryMatch {

  /** A MatcherFactory for producing ExplainingMatches */
  public static final MatcherFactory<ExplainingMatch> MATCHER =
      searcher ->
          new CandidateMatcher<>(searcher) {
            @Override
            public void matchQuery(String queryId, Query matchQuery, Map<String, String> metadata)
                throws IOException {
              int maxDocs = searcher.getIndexReader().maxDoc();
              for (int i = 0; i < maxDocs; i++) {
                Explanation explanation = searcher.explain(matchQuery, i);
                if (explanation.isMatch()) addMatch(new ExplainingMatch(queryId, explanation), i);
              }
            }

            @Override
            public ExplainingMatch resolve(ExplainingMatch match1, ExplainingMatch match2) {
              return new ExplainingMatch(
                  match1.getQueryId(),
                  Explanation.match(
                      match1.getExplanation().getValue().doubleValue()
                          + match2.getExplanation().getValue().doubleValue(),
                      "sum of:",
                      match1.getExplanation(),
                      match2.getExplanation()));
            }
          };

  private final Explanation explanation;

  ExplainingMatch(String queryId, Explanation explanation) {
    super(queryId);
    this.explanation = explanation;
  }

  /**
   * @return the Explanation
   */
  public Explanation getExplanation() {
    return explanation;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    if (!super.equals(o)) return false;
    ExplainingMatch that = (ExplainingMatch) o;
    return Objects.equals(explanation, that.explanation);
  }

  @Override
  public int hashCode() {
    return Objects.hash(super.hashCode(), explanation);
  }
}
